CALR and rheumatoid arthritis: The specific reactivity of one of our RA-rmAbs (RA057/11.89.1) with CRT was then confirmed by using at least three methods: 1) colocalization with anti-CRT in confocal microscopy; 2) Western blot using RA-FLS protein extracts and/or hrCRT as substrates and IP using CRT and the RA-rmAb, followed by LC-MS/MS analysis; and 3) ELISA using hrCRT with competitive binding assays.